A wide variety of deodorizing compositions are known in the art, the most common of which contain perfumes or fragrances to mask malodors. Odor masking is the intentional concealment of one odor by the addition of another. In order to mask odors using perfumes or fragrances, however, high levels of fragrance are generally needed to ensure that the malodor is no longer noticeable or suitably masked and the masking techniques do nothing to remove or modify the source of the odor. Aerosol spray air sanitizers are known in the art to effectively kill airborne microorganisms and mitigate airborne malodorants. The active ingredients in currently available aerosol air sanitizers vary. One family of products relies upon glycols, such as propylene glycol, dipropylene glycol and triethylene glycol. The most popular is triethylene glycol, the active ingredient in the OUST® family of products sold by S. C. Johnson & Son, Inc. Triethylene glycol (TEG) is known to kill certain airborne bacteria. TEG is also safe for use in aerosol sprays. Because the solubility of TEG in conventional hydrocarbon propellants is generally low, additional solvents, such as ethanol, are added to TEG-based aerosol compositions to increase the solubility of TEG in hydrocarbon propellants. Ethanol is also used as a co-solvent to increase volatility of the product and to make other components, such as fragrance oils, more soluble.
However, the use of ethanol and other conventional solvents in combination with conventional short C-chain aliphatic propellants limits the amount of TEG that can be included in a single-phase formulation. For example, the concentration of TEG in a single-phase aerosol composition using conventional hydrocarbon propellant is limited to no more than 6-8 wt. % with 30 wt. % propellant and the rest being ethanol. The use of TEG in amounts that exceed 12 or 15 wt. % normally results in a two-phase system, thereby requiring the consumer to vigorously shake the canister before use and foreclosing use of the formulation in a continuous or automated spray device. Single-phase aerosol products that do not require vigorous shaking are advantageous because consumers often forget to shake multi-phase products that require mixing and, because the performance of single-phase aerosol products is not dependent upon mixing, the performance of single-phase aerosols can be more consistent. In contrast, the efficacy of multi-phase aerosol products that require mixing can be somewhat inconsistent, especially if the user is physically unable to shake the can as vigorously as required.
Both ethanol and hydrocarbon propellants are considered to be volatile organic compounds. The content of volatile organic compounds in aerosol air sanitizers has the potential to be regulated by federal and/or state regulatory agencies, such as the Environmental Protection Agency (EPA) and California Air Resource Board (CARB). An existing single-phase TEG-based aerosol composition typically has a volatile organic compound content of more than 90 wt. %. By increasing the content of TEG, the volatile organic compound content of the aerosol composition can be reduced as well.